It may not be the shorter days and colder weather getting you down; it could be what you’re eating.
There is some thought in the scientific world, based on many studies, that some specific foods may be causing depression in some people. The idea is that there are certain foods that have been more recently introduced into the human diet which we have not had sufficient time to fully adapt to. As a result, we can’t break them down properly and they are causing problems inside our bodies.
Gluten has been the focus of this sort of research for a while because depression is a very common symptom of celiac disease (gluten allergy). Dairy products though, are another group of foods that we probably haven’t had enough time to fully adapt to, and may play a role in depression in some people.
Food isn’t a factor for all people suffering from depression, but dietary changes could potentially help many people. A gluten-free and/or dairy-free diet could be a natural, drug-free way for some people improve their mood and increase their quality of life.
Hoggan, Ron, M.A. and Braly, James, M.D. “Food Allergies and Depression” about.com. December 8, 2003.